When you add a link to a disambiguation page in VE, the class mw-disambig is set on the link, like in read view.
But this only works for newly added links, the class is missing for links already present when you start editing. (And it also isn't added when you add a new link to a disambiguation page that already was present before.)
To test: https://de.wikipedia.org/wiki/0 has the link 00, which has the mw-disambig class in read view, and thus should still have this class when you start editing in VE. According to T149794, Parsoid should actually be able to add that class, but apparently it is missing still.